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Volume 44 ， Issue 1 ， 2026
- Abstract：Physics-informed neural networks (PINNs), as a novel artificial intelligence method for solving partial differential equations, are applicable to solve both forward and inverse problems. This study evaluates the performance of PINNs in solving the temperature diffusion equation of the seawater across six scenarios, including forward and inverse problems under three different boundary conditions. Results demonstrate that PINNs achieved consistently higher accuracy with the Dirichlet and Neumann boundary conditions compared to the Robin boundary condition for both forward and inverse problems. Inaccurate weighting of terms in the loss function can reduce model accuracy. Additionally, the sensitivity of model performance to the positioning of sampling points varied between different boundary conditions. In particular, the model under the Dirichlet boundary condition exhibited superior robustness to variations in point positions during the solutions of inverse problems. In contrast, for the Neumann and Robin boundary conditions, accuracy declines when points were sampled from identical positions or at the same time. Subsequently, the Argo observations were used to reconstruct the vertical diffusion of seawater temperature in the north-central Pacific for the applicability of PINNs in the real ocean. The PINNs successfully captured the vertical diffusion characteristics of seawater temperature, reflected the seasonal changes of vertical temperature under different topographic conditions, and revealed the influence of topography on the temperature diffusion coefficient. The PINNs were proved effective in solving the temperature diffusion equation of seawater with limited data, providing a promising technique for simulating or predicting ocean phenomena using sparse observations.Keywords：temperature diffusion equation;physics-informed neural network (PINN);Boundary Condition;forward and inverse problem93|23|0Updated：2026-03-26
- Abstract：The prediction of sea surface partial pressure of carbon dioxide (pCO2) in the South China Sea is crucial for understanding the region’s contribution to the global carbon budget and its interactions with climate change. We applied the Spatiotemporal Convolutional Long Short-Term Memory (ST-ConvLSTM) model, integrating key environmental factors including sea surface temperature (SST), sea surface salinity (SSS), and chlorophyll a (Chl a), to predict and analyze sea surface pCO2 in the South China Sea. The model demonstrated high accuracy in short-term predictions (1 month), with a mean absolute error (MAE) of 0.394, a root mean square error (RMSE) of 0.659, and a coefficient of determination (R2) of 0.998. For long-term predictions (12 months), the model maintained its predictive capability, with an MAE of 0.667, RMSE of 1.255, and R2 of 0.994. Feature importance analysis revealed that sea surface pCO2 and SST were the main drivers of the model’s predictions, whereas Chl a and SSS had relatively minor impacts. The model’s generalization ability was further validated in the northwest Pacific Ocean and tropical Pacific Ocean, where it successfully captured the spatiotemporal variation in pCO2 with small prediction errors. The ST-ConvLSTM model provides an efficient and accurate tool for forecasting and analyzing sea surface pCO2 in the South China Sea, offering new insights into global carbon cycling and climate change. This study demonstrates the potential of deep learning in marine science and provides a significant technical support for global changes and marine ecosystem research.Keywords：sea surface carbon dioxide;South China Sea;Spatiotemporal Convolutional Long Short-Term Memory (ST-ConvLSTM);deep learning80|20|0Updated：2026-03-26
- Abstract：Bathymetric measurement of shallow water is of fundamental importance to coastal environment research and resource management. However, there are still great challenges in estimating water depth using satellite observations in turbid coastal waters. In this paper, we developed a physics-enhanced deep neural network to estimate bathymetry of highly turbid waters of the Changjiang (Yangtze) River estuary from dual-polarized synthetic aperture radar (SAR) images. Sentinel-1A/B SAR images with a spatial resolution of 20 m×22 m were collected and matched with water depth data from nautical charts during 2017–2023. For the input parameters of the model, in addition to the normalized radar backscatter cross section (NRCS) at single polarization and incidence angle, the impacts of both polarimetric characteristics and physical environmental factors on model performance were discussed in detail. Results of feature importance analysis and sensitivity experiments indicate that the polarization ratio and NRCS after removing the influence of background sea surface wind field make significant contributions to the bathymetry retrieval model. The root mean square error (RMSE) of SAR derived water depth decreases from 1.44 to 0.78 m within 0–30-m depth, and the mean relative error (MRE) is reduced from 15.6% to 8.6%. Compared with other machine learning models such as ResNet, XGBoost, and Random Forest, the MRE is reduced by 3.9%, 5.7%, and 7.4%, respectively. The spatial distribution of SAR derived water depth also exhibits a high degree of consistency with observations, demonstrating the great potential of the model in estimating the depth of turbid shallow waters.Keywords：shallow water depth;synthetic aperture radar (SAR);deep learning;Changjiang River estuary87|23|0Updated：2026-03-26
- Abstract：The study of mesoscale eddies is generally categorized in Eulerian or Lagrangian frameworks. We employed the eddy identification techniques in both frameworks in the South China Sea (SCS), examining the differential characteristics of mesoscale eddies ascertained through each approach, and attempting to identify factors influencing eddy lifetime. The findings suggest that eddies identified via the sea surface height (SSH) method in the Eulerian framework typically have larger spatial extents compared to those identified using the Lagrangian Average Vorticity Deviation (LAVD) method. The latter is characterized by a greater number of vortices with smaller average values of characteristic parameters. SSH eddies exhibited more remarked seasonal variations than LAVD vortices, and the seasonal variations of their respective cyclonic and anticyclonic eddies showed opposite trends. Analysis in both frameworks indicates that eddy lifetime is positively correlated with various eddy characteristic parameters, including radius, vorticity, kinetic energy, amplitude, EKE/MKE (ratio of boundary to spatial mean kinetic energy), and U/c (max rotation speed to mean propagation speed ratio). A subsequent comparison between SSH eddies with LAVD cores (SSH eddy with LAVD vortex inside) and those without reveals a greater likelihood of extended lifetime in the former. Compared to the characteristic parameters of eddies, the presence of LAVD cores emerges as a critical factor in determining the lifetime of SSH eddies.Keywords：South China Sea;mesoscale eddy;Eulerian method;Lagrangian method8|21|0Updated：2026-03-26
- Abstract：Internal solitary waves (ISWs) are an essential dynamic process in the ocean due to their large amplitude and long propagation distance. Traditional satellite observations provide only two-dimensional observations of ocean signatures induced by ISWs. The Surface Water and Ocean Topography (SWOT) satellite has drawn significant attention due to its high resolution and three-dimensional observation capabilities. SWOT can generate high-precision three-dimensional sea surface topography, capture sea surface undulations, and reveal ISW-related surface oscillations, thus offering a new perspective for studying ISWs. We collected 43 SWOT observations with clear ISW signatures in the Lombok Strait from August 2023 to June 2024. Based on collected data, the ISW imaging characteristics and distributions were analyzed, and the ISW-related sea level anomaly (SLA) data were measured by the SWOT to calculate the ISW amplitude and reveal the amplitude variations during the propagation along the wave crest. The ISW amplitudes generally range between 10 and 100 m, with most ISW amplitudes between 20 and 40 m. By analyzing two consecutive generated ISW packets, we identified the spreading effect along ISW wave crests, which manifests as ISW amplitude decrease with increase in propagation distance, and the amplitude distribution is non-uniform along the wave crest. Further analysis of the propagation paths of the maximum amplitude of ISW moving northward through the Lombok Strait revealed that these maxima are predominantly oriented in northeast direction. Finally, the relationship between the amplitude of ISW and the resulting SLA was analyzed. The Pearson correlation coefficient between these two variables is as high as 0.90, which suggests a strong positive correlation between amplitude and SLA. Furthermore, this relationship is closely related to the water depth, indicating that the three-dimensional sea surface observations provided by SWOT offer crucial observational data for the inversion of amplitudes of ISW.Keywords：internal solitary wave (ISW);Surface Water and Ocean Topography (SWOT);amplitude;Lombok Strait14|22|0Updated：2026-03-26
- Abstract：Precipitation nowcasting is of great importance for disaster prevention and mitigation. However, precipitation is a complex spatio-temporal phenomenon influenced by various underlying physical factors. Even slight changes in the initial precipitation field can have a significant impact on the future precipitation patterns, making the nowcasting of short-term high-resolution precipitation a major challenge. Traditional deep learning methods often have difficulty capturing the long-term spatial dependence of precipitation and are usually at a low resolution. To address these issues, based upon the Simpler yet Better Video Prediction (SimVP) framework, we proposed a deep generative neural network that incorporates the Simple Parameter-Free Attention Module (SimAM) and Generative Adversarial Networks (GANs) for short-term high-resolution precipitation event forecasting. Through an adversarial training strategy, critical precipitation features were extracted from complex radar echo images. During the adversarial learning process, the dynamic competition between the generator and the discriminator could continuously enhance the model in prediction accuracy and resolution for short-term precipitation. Experimental results demonstrate that the proposed method could effectively forecast short-term precipitation events on various scales and showed the best overall performance among existing methods.Keywords：precipitation nowcasting;deep learning;Simple Parameter-Free Attention Module (SimAM);Generative Adversarial Networks (GANs)11|21|0Updated：2026-03-26
Physics
- Abstract：Benthic habitat mapping is an emerging discipline in the international marine field in recent years, providing an effective tool for marine spatial planning, marine ecological management, and decision-making applications. Seabed sediment classification is one of the main contents of seabed habitat mapping. In response to the impact of remote sensing imaging quality and the limitations of acoustic measurement range, where a single data source does not fully reflect the substrate type, we proposed a high-precision seabed habitat sediment classification method that integrates data from multiple sources. Based on WorldView-2 multi-spectral remote sensing image data and multibeam bathymetry data, constructed a random forests (RF) classifier with optimal feature selection. A seabed sediment classification experiment integrating optical remote sensing and acoustic remote sensing data was carried out in the shallow water area of Wuzhizhou Island, Hainan, South China. Different seabed sediment types, such as sand, seagrass, and coral reefs were effectively identified, with an overall classification accuracy of 92%. Experimental results show that RF matrix optimized by fusing multi-source remote sensing data for feature selection were better than the classification results of simple combinations of data sources, which improved the accuracy of seabed sediment classification. Therefore, the method proposed in this paper can be effectively applied to high-precision seabed sediment classification and habitat mapping around islands and reefs.Keywords：Wuzhizhou Island;marine remote sensing;coastal mapping;multi-spectral remote sensing;shallow water reef;seabed sediment classification;benthic habitat mapping;multi-source data fusion;random forest (RF)10|23|0Updated：2026-03-26
- Abstract：Both natural and human-induced disturbances affect the normal functioning and services of mangrove ecosystems. To address the consequences of intense human and climatic disturbances on sedimentation and carbon burial, sediment cores from the last remaining mangrove Kandelia obovata forest and an adjacent mudflat in the densely populated and typhoon-prone Zhujiang (Pearl) River estuary of China, were analyzed using methods including 210Pb dating and δ13C analysis. Results indicate that after damming in the 1950s, during 1960–1980, the natural establishment of K. obovata forests initiated the in-situ sedimentation. As these forests matured during 1980–1990, they significantly boosted siltation in the region on mudflat. During 1990–2015, the invasion of Spartina alterniflora and land reclamation for aquaculture caused infiltration of coarse sediments and the impacts of typhoons were recorded within the K. obovata forest, while no clear typhoon record was observed on the mudflat. Since 2015, reforestation efforts with S. apetala that began in 1999 have reversed the effects of earlier deforestation. Over time, mangroves established a rapid autochthonous carbon burial that grew as the forests age, potentially surpassing the influx of allochthonous carbon due to deforestation. The reforestation also immediately improved carbon burial on the mudflat, which stabilized after a decade due to the rapid growth and high biomass of S. apetala. Overall, the K. obovata forest demonstrated a stronger sedimentation and carbon burial capabilities than the mudflat, with a surplus of 35.2 Mg C/hm2 in soil organic carbon stock and 1.0 Mg C/(hm2·a) in burial rate. Organic matter dissolved in soil was mainly humus-like components, and mangrove inputs likely increased the degree of humification. This study offered direct evidence regarding the impact of multiple disturbances on local and regional sedimentation and carbon burial, and future management strategies.Keywords：mangrove;deforestation;reforestation;allochthonous source;210Pb dating;δ13C57|16|0Updated：2026-03-26
Geology
- Abstract：While oceanic and coastal acidification has gained increased attention, long-term pH trends and their drivers in large freshwater systems remain poorly understood. The Laurentian Great Lakes are the world’s largest freshwater system, and in many ways resemble marine ecosystems. However, unlike the open ocean and coastal waters where pH has declined due to rising atmospheric CO2, no significant pH trends have been observed in the Laurentian Great Lakes, despite significant ecosystem changes driven partly by the invasion of dreissenid mussels. This study examined 41 years of field observations from Lake Michigan to investigate the long-term carbonate chemistry dynamics. Observational results revealed substantial declines in both total alkalinity (TA) and dissolved inorganic carbon (DIC) over the four decades. Mussel shell calcification emerged as the primary mechanism behind these declines, accounting for 97% and 47% of the observed changes in TA and DIC, respectively, lowering water column pH by 0.24 units. Elevated carbon accumulation in soft mussel tissues, coupled with long-term changes in the air-water pCO2 gradient during summer, significantly contributed to long-term DIC variations, explaining 18% and 28% of the lake-wide DIC loss. These two mechanisms also resulted in an overall pH increase of 0.09 and 0.12 units, largely offsetting the calcification-driven pH decrease. These findings bridge a gap in acidification research for large freshwater systems and provide valuable insights for comprehensive lake-wide management strategies.Keywords：carbonate chemistry;freshwater acidification;invasive mussel;Lake Michigan;long-term trend14|14|0Updated：2026-03-26
- Abstract：To simultaneously enrich, separate, and determine five fluoroquinolone antibiotics (FQs) in marine crude drugs (MCDs), seawater and seafood, we conducted this study using vortex assisted dispersed liquid-liquid microextraction (DLLME), followed by capillary electrophoresis (CE)-UV. A single-variable optimization was employed to examine the factors influencing the separation effect of CE and the extraction efficiency of DLLME, including buffer solution, organic solvent, separation voltage, extractant, dispersant, and sample solution pH. Under the optimal conditions, the baseline separation of the five FQs was achieved within 6 min. The analytical performance of the method was assessed using six types of actual samples, including three MCDs of hippocampus, clam, and kelp, seawater, and two seafood of prawn and pomfret, demonstrating good linearity ranging from 0.1–5 or 0.01–5 μg/mL. The limits of detection (LODs) and limits of quantification (LOQs) for the five FQs in MCDs were 0.002 2–0.029 2 and 0.006 6–0.097 3 μg/mL, respectively. The LODs and LOQs in seawater and seafood were 0.000 9–0.026 2 and 0.002 9–0.087 4 μg/mL, respectively. The matrix effects of this method were evaluated in the hippocampus, seawater, and prawn, and the results show that DLLME could effectively eliminate matrix interference. Satisfactory recovery rates were achieved in all the six tested actual samples. This developed DLLME-CE method was proven simple to operate, accurate and reliable, with high sensitivity, making it suitable for the analysis of multiple antibiotic residues in complex matrices.Keywords：fluoroquinolone antibiotic (FQ);dispersive liquid-liquid microextraction (DLLME);capillary electrophoresis (CE);marine crude drug (MCD);seafood;seawater9|15|0Updated：2026-03-26
- Abstract：Water-cooled system have significantly enhanced the power generation efficiency of offshore wind turbines. However, these innovative systems are susceptible to substantial biological fouling, maintenance challenges, and high upkeep costs. Therefore, the development of a specialized front-end filter tailored for direct current water-cooled system is importance. This involves the integration of dimensionally stable anode (DSA) and nickel alloy cathode, valued for their corrosion resistance in seawater, into a novel front-end filter system for Water-cooled applications. This system has the dual capability of generating hydrogen and chlorine for self-cleaning purposes. Implementing a flushing pulse electrolysis mode, it effectively mitigates electrode failure induced by cathodic calcium and magnesium deposition, thereby significantly prolonging electrode lifespan. Laboratory tests comprising system assembly and performance evaluations were conducted, with the system programmed to operate for 5 minutes every 24 hours under continuous flushing by natural seawater to simulate real-world conditions. After more than 11 months of continuous flushing, observations reveal that the DSA mesh and nickel alloy mesh maintain intact structural integrity and normal functioning. Subsequent 1꞉1 physical prototype Sea trial further validated the soundness of the system design and electrolytic control parameters.Keywords：water-cooled system;pulse electrolysis;antifouling;dimensionally stable anode (DSA);nickel alloy;offshore wind turbine8|10|0Updated：2026-03-26
Chemistry
- Abstract：Giant kelp Macrocystis pyrifera, an important foundation species with great ecological and economic value, is threatened by climate change. To better understand the impact of climate warming on M. pyrifera, we investigated its global distribution dynamics by an optimized species distribution model (SDM). Results showed that wave height, sea surface temperature, benthic temperature, and benthic phosphate concentration were key factors shaping the distribution of M. pyrifera. In addition to currently known distribution regions, the model revealed potential suitable habitats globally. Under future climate scenarios, the habitat suitability of M. pyrifera would decrease at low latitudes and increase at high latitudes, resulting in a poleward shift of suitable habitats. In the regions currently occupied by M. pyrifera, the high suitable habitats were predicted to shrink, which implies that the existing M. pyrifera would be adversely impacted. These results serve as references for the conservation and utilization of M. pyrifera resource.Keywords：Macrocystis pyrifera;kelp forest;species distribution model (SDM);Maxent;climate warming61|4|0Updated：2026-03-26
- Abstract：Nutrients play a crucial role in sustaining marine ecosystems and supporting mariculture, especially in seaweed aquaculture. Currently, seaweed farming, such as kelp cultivation, is entirely dependent on the natural supply of nutrients. Sanggou Bay in Shandong Peninsula, Yellow Sea, is renowned for its 60-year history of kelp cultivation; however, it is recently facing an increasing demand for nitrogen and phosphorus due to the expansion in aquaculture scale and production. There is no doubt that nutrient addition can enhance and sustain the production, but it is crucial to understand its effect on kelp growth under current nutrients condition and the potential ecological risks. Our in-field nutrient enrichment experiments show that nitrogen and phosphorus additions promoted the kelp biomass during the early growth stages, and have no adverse effects on phytoplankton or seawater nutrient levels throughout the experiment. From a long-term perspective, increasing nutrient supply appears to be an essential strategy for sustaining the aquaculture of kelp.Keywords：kelp;nutrient enrichment;nitrogen and phosphorus;Sanggou Bay;kelp aquaculture7|4|0Updated：2026-03-26
- Abstract：Ecological floating bed is an important biological remediation method for water pollution control. During the removal of excess nutrients and pollutants, changes in environmental factors affect the characteristics of microorganisms in aquatic ecosystems. To understand the influences of ecological floating beds on size-fractionated microorganisms, we investigated the community assembly and nitrogen metabolic characteristics of three size-fractionated microorganism groups in the ecological floating bed area, using 18S rDNA, 16S rDNA metabarcoding, and metagenomic sequencing techniques. Firstly, we discovered substantial differences between size-fractionated groups in the diversity and compositions of both microeukaryotic and bacterial communities, as well as the influences of floating beds on specific groups. The floating beds appeared to provide more habitats for heterotrophs and symbiotes while potentially inhibiting the growth of certain phytoplankton (cyanobacteria). Secondly, we observed that microeukaryotic and bacterial communities were predominantly influenced by stochastic and deterministic processes, respectively, and they both exhibited distinct patterns across different size-fractionated groups. Notably, microeukaryotic community assembly demonstrated a greater sensitivity to ecological floating beds, as indicated by an increase in dispersal limitation processes. Finally, the nitrogen metabolism functional genes revealed that microbes associated with large-sized particles played a crucial role in dissimilatory nitrate reduction to ammonium (DNRA) and denitrification processes within the floating bed area, thereby facilitating the removal of excess nitrogen nutrients from the water. In contrast, free-living microorganisms from small-sized groups were linked mainly to the genes involved in nitrogen assimilation and assimilatory nitrate reduction to ammonium (ANRA) processes. These findings help understand the impact of ecological floating beds on the diversity and functional characteristics of microorganism communities in different size-fractionated groups.Keywords：size-fractionated;microorganism;metagenomic;nitrogen metabolism;assembly process;ecological floating bed10|9|0Updated：2026-03-26
- Abstract：Marine pollution and overfishing induced the biodiversity loss and ecological degradation of the Beibu Gulf ecosystem in Guangxi, SE China. In an effort to restore the ecosystem and fishery resources, artificial reefs were deployed in the Beibu Gulf as the marine ranching area and their ecological performance need to be investigated. We constructed Ecopath ecological trophic models for the marine ranching area and a nearby control area to compare their ecosystem throughput and food web structure difference, and to calculate the ecological carrying capacity of various functional groups. Results indicate that the total system throughput of the marine ranching area was significantly higher than the control area, and the majority of system throughput occurred at trophic levels Ⅰ and Ⅱ in both ecosystems. The system connectance indices for the marine ranching and control areas were 0.27 and 0.32, and the omnivory indices were 0.16 and 0.19, indicating simple food web structures; both areas are in a developmental stage with TPP/TR ratios of 2.69 and 9.36, respectively. Compared to the control area, marine ranching area exhibited a higher system maturity, and the ecological carrying capacity of “large and medium-sized demersal fish” and “other bivalves” functional groups in the marine ranching area increased by 43.83% and 233.62%, respectively, allowing for more high-trophic-level predators and large benthic animals. This study provided a reference for the formulation of fishery management policies in the Beibu Gulf, to maintain ecosystem stability and biodiversity.Keywords：marine ranching;Ecopath;ecosystem maturity;trophic structure13|4|0Updated：2026-03-26
- Abstract：Stichopus chloronotus is a tropical sea cucumber with facultative asexual reproduction in the Indo-Western Pacific, yet its wild populations are decreasing due to extensive harvesting. Understanding the species’ genetic characteristics is essential for effective management and conservation. To develop novel microsatellite markers and assess the genetic diversity, clonality, and genetic structure of eight populations of S. chloronotus in the South China Sea, 193 individuals from eight populations across Wuzhizhou and Fenjiezhou (Boundary) islands were analyzed using nine newly developed microsatellite markers and five previously established markers. RNA-Seq was employed to obtained 62 662 unigenes and identified 16 926 microsatellite loci. Fourteen polymorphic microsatellite loci were developed, of which 11 were highly polymorphic (polymorphic information content>0.5). The number of alleles (Na) ranged from 3 to 6 per locus, and the average Shannon diversity index (I) was 1.107. All the populations exhibited asexual reproduction, with regional variations in reproductive modes. Asexual reproduction was predominant in the northwestern Wuzhizhou Island population (SY 7) and the Fenjiezhou Island population (LS 8), where four and five predominant clones represented more than 89% of the individuals, which led to reduced genetic diversity. Overall, genetic diversity was moderately low, with significant genetic differentiation among populations (FST=0.33; P<0.001), suggesting limited gene flow (the number of migrants (Nm)<1). These findings highlight the role of reproductive strategies in shaping fine-scale genetic differentiation in S. chloronotus. The limited recruitment success of sexually produced larvae and habitat heterogeneity likely constrain clone dispersal, contributing to distinct genetic restructuring. This study provided key insights into the interplay between reproductive strategies and genetic patterns in sea cucumbers, offering a scientific basis for targeted conservation efforts.Keywords：Stichopus chloronotus;microsatellite marker (SSR);population genetic diversity;asexual reproduction9|2|0Updated：2026-03-26
- Abstract：Pelagic appendicularians, known for their rapid bloom capability, are important secondary producers and play essential roles in marine ecosystems. To assess the environmental adaptation of the most common appendicularian species Oikopleura dioica in Jiaozhou Bay, Shandong, China, its annual variations in abundance and body size were investigated monthly at 12 stations in 2011, and the relationship between somatic growth and gonadal development was compared with previously published laboratory data. Oikopleura dioica exhibited distinct seasonal abundance patterns, peaking in summer and autumn, particularly in the inner bay, reflecting its adaptation to the eutrophic conditions and high food availability. Compared to laboratory results, O. dioica in Jiaozhou Bay exhibited shorter body lengths, smaller gonad volumes, and earlier maturation at reduced body sizes, despite high natural chlorophyll-a concentration, suggesting that factors beyond food availability, such as resource competition and environmental stressors, may limit its growth in natural settings. Correlation analysis indicated that the somatic growth of natural O. dioica was primarily influenced by temperature, while gonadal development was related to chlorophyll-a concentration, and its population abundance was linked to food availability and the abundance of other zooplankton, such as copepods and jellyfish. It was suggested that the growth and recruitment of O. dioica were constrained by resource limitations in natural environments, further exacerbated by interactions with other zooplankton, including predation and competition. This study provides valuable data on the mechanisms underlying bio-environmental interactions and their spatiotemporal variations, offering critical insights into the ecological roles of appendicularians in marine ecosystems.Keywords：Oikopleura dioica;body size;size-at-maturation;food limitation;Jiaozhou Bay;population recruitment7|2|0Updated：2026-03-26
- Abstract：Microbial communities play indispensable roles in the biogeochemical cycling of river ecosystems. However, the response patterns of microbial community diversity, niche breadth, and assembly to rainfall disturbances in complex mountainous riverine reservoirs remain inadequately understood. We employed high-throughput sequencing of 16S and 18S ribosomal RNA genes, along with multivariate statistical methods to systematically investigate prokaryotic and eukaryotic microorganisms in the riverine Zhaoshandu Reservoir, Wenzhou, Zhejiang, East China. Results show significant temporal heterogeneity in both prokaryotic and eukaryotic microbial communities, with eukaryotic microbes showing more pronounced temporal variation. Canonical correspondence analysis revealed that rainfall and water temperature were the key drivers shaping microbial communities. Additionally, eukaryotic microorganisms exhibited a more pronounced response to rainfall and water temperature compared to prokaryotes. Modified stochasticity ratio model indicated that deterministic processes predominantly governed microbial community assembly, with stronger deterministic processes in eukaryotic compared to prokaryotic microorganisms. Rainfall has significantly altered water quality, notably increasing phosphorus concentration in the water column. Total phosphorus and total nitrogen showed significant correlations with the niche breadth of prokaryotic and eukaryotic microorganisms, and phosphorus nutrients served as keystones and playing indispensable roles in their co-occurrence networks. A structural equation model confirmed the notable impacts of rainfall and water temperature on microbial community diversity, further revealing that rainfall indirectly influenced the niche breadth and co-occurrence relationships of microbial communities by altering phosphorus concentrations. The findings underscore the influence of rainfall and water temperature on microbial distribution, highlighting the sensitivity of riverine reservoir ecosystems to climate change.Keywords：riverine reservoir;rainfall disturbance;ecological process;co-occurrence network;phosphorus7|7|0Updated：2026-03-26
- Abstract：In natural aquatic ecosystems, algal-derived organic carbon (AOC) often coexists with exogenous organic carbon (EOC). Microbial utilization of these distinct carbon sources affects carbon flux and transformation in water column and algal growth. Microcystis blooms significantly increase AOC levels in water, but the microbial transformation process of Microcystis-derived AOC in the presence of EOC remain poorly understood. We conducted a simulated experiment by introducing 13C-sodium bicarbonate and 13C-glucose as substrates for indoor simulation of non-axenic Microcystis aeruginosa (M. aeruginosa) populations in a sealed system. The microbial transformation processes of AOC and EOC and their effects on M. aeruginosa growth were investigated. Results demonstrated that the addition of glucose accelerated M. aeruginosa growth and significantly increased their biomass. During the experiment, as the particulate organic carbon and nitrogen content increased, the concentrations of CO2 and N2O were gradually decreased, while the concentration of CH4 were gradually increased. Significant differences were observed in the microbial processes involved in the uptake of AOC and EOC. Bacteria involved in AOC transformation throughout the growth period were dominated by Proteobacteria, Gemmatimonadota, Actinobacteriota, Bacteroidota, Acidobacteriota, and Firmicutes. The bacteria involved in EOC transformation were dominated by Proteobacteria, Actinobacteriota, Firmicutes, Cyanobacteria, Armatimonadota, and Bacteroidota. Linear discriminant analysis Effect Size (LEfSe) analysis revealed Massilia and Akkermansia as biomarkers involved in AOC transformation, while Ligilactobacillus was associated with EOC transformation. These findings provide valuable insights into the effects of EOC on algae-bacteria interaction, and on the dynamics of carbon and nitrogen cycling among M. aeruginosa and its associated bacteria.Keywords：Microcystis aeruginosa;associated bacteria;algal-derived organic carbon;exogenous organic carbon;DNA-based stable isotope probing (DNA-SIP)22|5|0Updated：2026-03-26
Ecology
- Abstract：Stephanodiscaceae is one of the most diverse family of the freshwater centric diatoms. However, the scarcity of whole plastome data poses a significant challenge to the undertaking of genomic studies on this taxonomic group. We collected data on the plastid genomes from 33 members of the Stephanodiscaceae and its close relatives, including 12 newly-sequenced genomes and 21 deposited in National Center for Biotechnology Information (NCBI). Phylogenetic trees are yielded five major clades based on homologous genes. The features of the plastid genomes, including repeat sequences, codon usage, and selection pressure for each clade, are analyzed. The paper makes a contribution to the field of diatom genomics by describing the structural characteristics of the plastid genomes in the Stephanodiscaceae and its closely related species, complemented by related analyses. It provides crucial data that will serve as indispensable references for future research.Keywords：chloroplast genome;phylogenomics;plastome evolution;Stephanodiscaceae12|5|0Updated：2026-03-26
- Abstract：This study presents a comprehensive phylogenetic analysis on Batrachospermaceae based on key taxonomic identifiers (rbcL, psaA, psbA, and COI-5P) from some genera. To systematically explore the phylogenetic relationships and taxonomy within Batrachospermaceae, we integrated molecular and morphological data, and explored the phylogeny, character evolution, and ancestral geographical origin and provided a theoretical support for the classification and geographic origination of Batrachospermaceae. Our findings reveal distinct relationships within the phylogenetic tree. Notably, 10 genera (Sirodotia, Batrachospermum, Tuomeya, Volatus, Lympha, Nothocladus, Torularia, Sheathia, Nocturama, and Petrohua) are closely associated in the rbcL phylogenetic tree. Additionally, four genera (Kumanoa, Hoefkenia, Notohesperus, and Virescentia) exhibit high support ratios, indicating their close interrelations. Other genera, including Paludicola, Visia, Acarposporophycos, Macrosporophycos, Visioidea, Balliopsis, and Psilosiphon, exhibit clustering traits. Furthermore, the multigene sequences provide a robust support for Montagnia that forms a monophyletic group. Ancestral reconstruction of morphological characters identifies nine primitive character states, including whorl, fascicle length, cortical cells, secondary fascicles, the shape of carpogonical branch, spermatangia, carposporophyte, carpogonium and trichogyne, with Visia likely representing ancestral traits in Batrachospermaceae. Furthermore, geographical origin maps suggest a potential common ancestral of Batrachospermaceae origin in the American continent. Additional to conventional analyses, including evolutionary and ancestral reconstruction investigations into key morphological characters, we attempt to reconstruct the biogeography within the Batrachospermaceae, thus contributing to a nuanced understanding of its origin.Keywords：Batrachospermaceae;phylogeny;morphological evolution;biogeographic reconstruction10|6|0Updated：2026-03-26
- Abstract：Nereididae is a prolific annelid family widely distributed in the world oceans, especially in the Indo-Pacific Convergence Zone (IPCZ). However, its biogeographic pattern remains unexplored in IPCZ. To contribute to the understanding of biodiversity and biogeography of Nereididae in the IPCZ, we integrated historical data of species distributions with those of model-predicted ones to determine the biogeographic patterns of nereid species, from which we projected to its future distribution patterns for 2090–2100 under different climate scenarios (SSP1-1.9 and SSP5-8.5). Functional diversity within IPCZ was assessed using functional richness, functional evenness, and functional disparity. Divergence times within Nereididae were estimated using three DNA marker genes (COI, 16S, and 18S rRNA), and a time tree was constructed based on a strict molecular clock model. The IPCZ was established as a key Nereididae biodiversity hotspot through distribution modelling of 256 species (44 genera), and temperature emerging as the predominant climatic driver of species distribution patterns. The distribution of species and functional diversity is notable for its non-centralized pattern. We projected that by the end of the century, areas of medium-to-high species richness will expand significantly under the low-emission SSP1-1.9 climate scenario. However, under the high-emission SSP5-8.5 scenario, the suitability of these regions significantly declines, posing an increasingly severe threat to biodiversity. In addition, by molecular clock analysis, we revealed that the evolutionary divergence of extant nereidid species occurred mainly in the Cretaceous and Jurassic, suggesting that paleogeographical and environmental events, such as oceanic anoxic events, might have played a pivotal role in shaping the evolutionary trajectory and ecological adaptations of marine annelids. These findings highlight the importance of considering both current biodiversity patterns and historical contexts in conservation planning, and provided insights into the potential factors on the biogeographic distribution and evolutionary processes of Nereididae.Keywords：Nereididae;species distribution model (SDM);climate change;biodiversity;Indo-Pacific Convergence Zone (IPCZ)9|7|0Updated：2026-03-26
- Abstract：Due to the unique microstructure and diverse opsin genes of the trinocular compound eye, stomatopoda possess an extraordinary ability to perceive multiple properties of light. They not only can detect natural light (NL) and linearly polarized light (LPL), but also are the only animals capable of recognizing circularly polarized light (CPL). Here, we integrated single-cell RNA sequencing, previously published Illumina data, and in-situ hybridization (ISH) to quantify and localize functional opsin genes in Oratosquilla oratoria, a common stomatopoda species in the China Sea. A total of high-quality 31 777 cells were captured for the first time in the O. oratoria compound eye, which were classified into 25 cell subpopulations, and hypothesized that cluster 22 is a critical cell subpopulation responsible for light (whether NL, LPL, or CPL) response in O. oratoria. Furthermore, we propose that the long-wavelength-sensitive opsin gene (lws) gene family, retinol dehydrogenase (rdh), voltage-gated ion channel (vgic), arrestin (arr), and myosin (myo) collectively mediate the light response in O. oratoria. Considering that very few vision-related opsin genes show differential expression in right-handed CPL (RCPL)-vs.-dark (DL), which provides additional evidence that stomatopoda cannot recognize RCPL. Meanwhile, we believe that UV-stimulated scaffold protein A (uvssa) and red pigment concentrating hormone (rpch) play special contributions in the left-handed CPL (LCPL) environment response. ISH revealing that 16 lws, 6 middle-wavelength-sensitive (mws), and 2 ultraviolet (uv) opsin genes were expressed in the photoreceptors of the O. oratoria compound eye. Although the inability to determine the functional types of cell subpopulations limits the resolution of opsin genes, these findings systematically elucidate the specific expression patterns of opsin genes in O. oratoria and represent a significant step toward refining the visual ecological theory of O. oratoria and other stomatopod species.Keywords：Oratosquilla oratoria;opsin gene expression pattern;single-cell RNA sequencing;in-situ hybridization7|2|0Updated：2026-03-26
- Abstract：The Saccostrea mordax Gould, 1850 is a typical intertidal species, whose genetic differentiation is influenced by various factors, including geological and climatic changes. To explore the genetic structure and historical population characteristics of Saccostrea mordax, we sequenced the mitochondrial cytochrome c oxidase subunit I (COI) gene from 58 specimens sampled from four locations in the western Pacific. Additionally, 103 individuals from the Persian Gulf and western Pacific (from databases) were included for phylogenetic analysis. The Bayesian Inference tree showed that all specimens were divided into two clades, i.e., the Persian Gulf population and the western Pacific population. Spatial molecular variance analysis indicated significant genetic differentiation between the two populations, and isolation by distance analysis revealed a positive correlation between genetic differentiation and geographic distance. Neutrality tests and Bayesian Skyline Plot suggested that both populations underwent expansions during the late Pleistocene. This study revealed the population history of Saccostrea mordax and described a new lineage, Saccostrea mordax lineage D, providing a foundation for understanding oyster biodiversity formation and genetic resource conservation.Keywords：Saccostrea mordax;cytochrome C oxidase subunit I (COI);genetic structure;population expansion;Saccostrea mordax lineage D8|2|0Updated：2026-03-26
- Abstract：With the increasing accumulation of plastic pollutants in various environments, research on microorganisms (including bacteria, fungi, and algae) with plastic degradation capabilities has gained significant attention. However, only a limited number of microbial plastic-degrading enzymes have been identified to date. This highlights that the degradation mechanisms employed by many plastic-degrading microorganisms, particularly filamentous fungi, remain insufficiently explored. In this study, we utilized a versatile fungal plasmid (pCT74) to express green fluorescent protein (GFP) in a marine-derived fungus Alternaria alternata strain FB1 with plastic degradation capabilities. Upon evaluating the degradation effect of polyester-type polyurethane (PU) film, we observed that different transformants exhibited three kinds of activities (the same, reduced, or enhanced degradation capability) compared to the FB1 wild-type strain. Further analysis of the plasmid fragment insertion sites in different transformants revealed that pCT74 integrates randomly into the genome of the host fungus. Notably, a direct correlation was found between the plasmid insertion site and the degradation capability of the corresponding transformant. Our findings not only redefine the potential applications of plasmid pCT74 in filamentous fungi but also show a novel research approach to identifying key enzymes involved in plastic degradation by fungi.Keywords：mutant library;green fluorescent protein;plastics biodegradation;Alternaria alternata;filamentous fungi;plasmid pCT749|4|0Updated：2026-03-26
- Abstract：Alzheimer’s disease (AD) is a complex neurodegenerative disorder associated with changes in inflammation, oxidative stress, and gut microbiota composition. Butyrolactone I (BTL-I), a fungal metabolite, has shown anti-inflammatory, microbiota regulating, and memory-improving potentials in previous in vitro and AlCl3-induced zebrafish studies. However, its effects of memory-improving and gut-brain axis regulating on Aβ-induced mammalian AD models have not been explored. In this study, intragastric administrated BTL-I ameliorated cognitive deficits related to recognition and spatial memory impaired by Aβ1-42 intracerebroventricular injection in mice. BTL-I maintained gut microbiota balance by increasing the abundance of Blautia, Muribaculaceae, Bacteroides, Akkermansia, etc., and decreasing CAG-352, Clostridia UCG-014, different Lachnospiraceae groups, etc., and Firmicutes/Bacteroidota ratio and elevated the levels of short-chain fatty acids. Additionally, it alleviated intestinal oxidative stress, inflammatory responses, and pathological damage. Furthermore, BTL-I reversed Aβ1-42-induced activation of microglia and astrocytes in the hippocampus and inhibited the elevated oxidative stress and pro-inflammatory cytokines in both plasma and brain. The correlation analysis between the regulated taxa and biomarkers supports the role of gut microbiota in adjusting inflammation, oxidative stress, and memory. In conclusion, BTL-I may serve as a valuable drug lead for treating Alzheimer’s disease by systematically inhibiting microbiota imbalance, inflammation, and oxidative stress along the gut-brain axis.Keywords：Alzheimer's disease;butyrolactone I;cognitive deficit;microbiota composition;oxidative stress;neuroinflammation12|3|0Updated：2026-03-26
Biology
- Abstract：Crassostrea gigas has good taste and high nutritional value; however, there are few assessments of comprehensive and panoramic analyses of the nutritional quality of the northern oyster. To study the nutritional characteristics of C. gigas from different sources (ploidy, region, size, and culture mode), C. gigas from various ploidy (diploid and triploid), regions (Rushan, Off-site fattening, and Rongcheng), sizes (small, medium, and large) and culture modes (nearshore and offshore) were selected for comparative analyses. The nutritional components (moisture, protein, fat, and mineral), flavor substances (taste amino acids, nucleotides, and succinic acid), and functional indices (eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and taurine) of C. gigas were determined. Principal component analysis (PCA) was used to comprehensively evaluate the oysters and investigate the variations in nutritional quality. The PCA results indicate that protein, essential fatty acids, selenium, zinc, taste amino acids, taurine, EPA, and DHA were core components contributing to 82.25% of the cumulative variance, providing a more comprehensive reflection of the nutrient composition of C. gigas. The extensive quality rankings for the C. gigas were as follows: diploid>triploid, Rushan>fattening>Rongcheng, medium>large>small, and offshore>nearshore. The score rank revealed that diploid oysters of medium-size from Rushan demonstrated superior nutritional quality compared to other tested samples. This is the first comprehensive and systematic investigation of C. gigas in northern China to reveal the feature of nutrients, flavor, and functional components. The study provided data support for the culture, consumption, processing, research, and nutritional quality improvement of oyster industry.Keywords：Crassostrea gigas;nutritional quality;principal component analysis;comprehensive evaluation5|2|0Updated：2026-03-26
- Abstract：The Fujian oyster (Crassostrea angulata) is an economically significant shellfish species distributed mainly along the Fujian coast, Southeast China. However, its genetic diversity and structure remain unclear. The main distribution area of the C. angulata is located in Fujian, South China. In total, 420 C. angulata were collected from 14 natural habitats (populations) along the Fujian coast, and their genetic diversity and structure were analyzed in the mitochondrial COⅠ and nuclear gene ITS2 sequences. Results reveal that all the 14 populations of C. angulata exhibited high levels of genetic diversity, with a total of 57 (haplotype diversity: 0.811±0.016) and 124 (haplotype diversity: 0.912±0.007) haplotypes revealed by COⅠ and ITS2, respectively. Notably, significant intermediate level of genetic differentiations between the Ningde Zhujiang (ZJ) population (FST by COI: 0.035–0.142, P<0.05; FST by ITS2: 0.078–0.123, P<0.05) with other populations were observed for the first time, which is also supported by the results of molecular variance analysis (FCT by COⅠ: 0.105, P<0.05; FCT by ITS2: 0.086, P<0.05) and the clustering of the ZJ population into distinct branches in the interpopulation genetic differentiation tree. Furthermore, the evolutionary tree and haplotype network analyses do not support the formation of a clear geographical genealogical structure among these 14 populations. In addition, the population dynamics analysis suggests that the C. angulata may have undergone expansion during the third ice age of the Pleistocene. These results provide a reference for the preservation and further genetic improvement of C. angulata.Keywords：Crassostrea angulata;genetic diversity;population structure;mitochondrial COⅠ gene;nuclear gene ITS2 sequence9|5|0Updated：2026-03-26
- Abstract：Atmospheric carbon dioxide (CO2) levels are escalating at an unprecedented rate, leading to the phenomenon of ocean acidification (OA). Parental exposure to acidification has the potential to enhance offspring resilience through cross-generation plasticity. In this study, we analyzed larval growth and transcriptomic profiles in the Pacific oyster, Crassostrea gigas, a species of significant ecological relevance, under both control and elevated CO2 conditions experienced by their parental generation. Our findings indicate that the oyster populations exposed to OA exhibited a higher incidence of abnormalities during the D-shaped larval stage, followed by accelerated growth at the eyed stage. Through a comparative transcriptomic investigation of eyed larvae (25 d after fertilization), we observed that parental exposure to OA substantially influenced the gene expression in the offspring. Genes associated with lipid catabolism and shell formation were notably upregulated in oysters with parental OA exposure, potentially playing a role in cross-generational conditioning and conferring resilience to OA stressors. These results underscore the profound impact of OA on oyster larval development via cross-generational mechanisms and shed light on the molecular underpinnings of cross-generation plasticity.Keywords：cross-generation plasticity;oyster;ocean acidification (OA);larval development;transcriptome8|4|0Updated：2026-03-26
- Abstract：Decapod Iridescent Virus 1 (DIV1) is a recently discovered virus recognized for its high infectivity in Macrobrachium rosenbergii. A thermal treatment was performed on DIV1-infected M. rosenbergii, and the therapeutic efficacy was evaluated. In the DIV1 challenge experiment, the mortality rate in the challenged group was found to be 2.6 times greater than that in the control group, with the viral load in deceased individuals exceeding 5.41×107 copies/μg-DNA. The thermal treatment (TT) was administered at 36 °C for a duration of 16 d, followed by a temperature restoration (TR) period at 26 °C for 3 d. On the first day at 36 °C, an average viral concentration of 5.34×10 copies/μg-DNA was detected in the survived individuals. RNA-seq analysis showed a significant upregulation of genes related to the lysosome pathway, including sialin-like isoform x2 (slc17a5), beta-galactosidase-1-like protein 2 (glb1), putative glucosylceramidase 3 (gba), sphingomyelin phosphodiesterase-like isoform x2 (smpd1), beta-hexosaminidase subunit alpha-like (hexa_b) and legumain-like protein (lgmn), following a transient suppression period induced by thermal stress. Upon reaching 36 °C, the activation of heat shock protein 70 (hsp70) and heat shock protein 90 (hsp90a) was observed. Concomitantly, genes that implicated in energy production critical for DIV1 replication, such as hexokinase (hk) and microsomal glutathione s-transferase 3-like isoform x2 (gst), were inhibited. These results collectively suggest that TT/TR treatments eliminated DIV1 in M. rosenbergii by activating the organism’s innate immune response and suppressing virus replication. This study provides a theoretical basis for utilizing thermal therapy in the management of viral infections in M. rosenbergii breeding programs, thereby facilitating the development of new strains resistant to DIV1.Keywords：Decapod Iridescent Virus 1 (DIV1);Macrobrachium rosenbergii;RNA-Seq;thermal treatment9|4|0Updated：2026-03-26
Aquaculture and Fisheries
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